Winding for electrical apparatus



L. H. BURNHAM. WINDING FOR ELECTRiCAL APPARATUS. APPLICATION FILED Jun 17 1918.

1,886,888. j Patented Aug. 9,1921

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UNITED STATES PATENT FFICE.

LOCKE H. IBURNHAM, OF PITT'SFIELD, MASSACHUSETTS, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A. CORPORATION OF NEW YORK.

WINDING ELECTRICAL. APPARATUS.

Application filed July 17,

struction and arrangement of the windings.

More especially my invention relates to transformers, some reactances and the like, inwhich it is necessary to interpose additional insulation between the windings, also the windings and the core and has for one of its particular objects an improved arrangement of the insulating material with respect to the windings whereby the socalled space-factor of the apparatus is improved.

In transformers, reactances and the like it has been customary, where designed for high tension duty, to divide the windings into groups or sections, each section being insulated from the other.

Barriers of insulating material are commonly interposed or interlaced therebetween, which barriers are generally extended beyond the edge of the windings a considerable distance in order to increase the creepage distance.

These extended barriers obviously require a larger inclosing casing than would be required were the barriers dispensed with. The use of such barriers consequently decreases the space-factor or ratio of the winding space to the total cross section of the windings.

In the practice of my invention I have so disposed the insulating material about the windings that the extension of the barriers inside or outside is greatly reduced and in some cases is unnecessary. This I accomplish by having the insulating material, interposed between sections of the windings,

conform with and bend partially over the edge of the windings.

This overturned edge of interposed insulation avoids the necessity for extended barriers and at the same tlme but partially envelops the windings so that a cooling medium may circulate over the edge of the Specification of Letters Patent.

Patented Aug. 9, 1921.

1918. Serial No. 245,330.

coils to effectually cool and ventilate the windings.

For a more complete understanding of the nature and objects of my invention reference should be had to the following detailed description when taken in connection with the accompanyingdrawings in which Figure 1 is a perspective view of atransformer winding embodying my invention; Fig. 2 is a partial sectional view; while Fig. 3 is an enlarged view to show in detail certain features of the insulation employed.

Referring now to the drawings, 10 denotes a transformer core constructed of iron or other magnetic material having two outer legs 11 and 12, and one central leg 13 about which the transformer windings 14c are assembled.

The windings 14 comprise coiled conductors and are shown as divided into groups or sections; lddenoting low voltage disk coils while 16 denotes a group of high voltage disk-coils.

These windings are spaced apart by suitable insulating collars 17 and suitable'radially disposed insulating strips 18.

In lieu of barriers, I have formed the interposed insulating material so as to bend over and conform with the edge of the coils 16 of the high voltage group. This is preferably accomplished by wrapping a group of coils 16 with one or more layers of insulating tape as shown at 20, which tape may be coated with varnish or shellac if desired so as to form an insulating jacket of a desired dielectric strength.

The jacket 20 serves to insulate the windings 16 from the core 10, and as additional insulation between the high voltage and low voltage group of coils, but since such insulation is not needed on the outer edges of the coils where not adjacent to the core 10, this insulation is conveniently cut away to. provide windows or openings about those portions of the edges of the coils which are not'adjacent to the core legs; leaving an over-hanging peripheral portion curving over the exposed edge of both the lower and upper coils 16 as indicated at 21.

he cutting away of the insulating jacket 20 in this manner not only effects the desired formation of insulating material over the edge of coils 16 so that projecting barriers may be dispensed with but the edges of the coils 16 are thus exposed, for a large portion of their circumference to the cooling medium such as oil, insulating compound, or air which surrounds the coils so that the group of coils 16 are more effectually cooled than if entirely inclosed.

The invention'while disclosed in connection with core type transformers, is obviously equally applicable to shell type transformers and to some reactors.

Having now described what is at present the best means known to me for carrying out an embodiment of my invention, would have it understood that such means are merely illustrative and that I do not mean to be limited thereby to the exact details shown nor in the choice of recognized equivalents except as defined in my claims hereunto appendedr What I claim as new and desire to secure by Letters Patent of the United States, is

1. In an electrical apparatus, the combination with a core of magnetic material, of electrical windings assembled'thereon comprislng coils disposed in spaced relation and (1 arranged in groups, and insulating material arranged in layers about a group of said colls; said insulating material having'a window formed in its cylindrical sides thereby exposing the edges of'said coils to a cooling and ventilating medium.

2. In an electrical apparatus, the combination with a core of magnetic material, of electrical windings assembled thereon comprising coils disposed in spaced relation and arranged in groups, and insulating material arranged in layers forming a jacket about a group of said coils; said jacket being formed with Windows in its cylindrical sides extending about the edges of the coils to points adjacent the core whereby the edges of the jacketed coils are exposed to the action of a cooling and ventilating medium.

3. In an electrical apparatus, the combiposed edges of the upper and lower coils in the group. 4.In an electrical apparatus, the combnation with a core of magnetic material, of

electrical windings assembled thereon comprising coils disposed in spaced relation and arranged in groups, and insulation arranged in layers forming a jacket about each of a plurality of groups of said coils; each of said jackets being formed with windows in their cylindrical sides extending about the edges of said coils to points adjacent the core, the peripheral portions of said winows comprising layers of insulating material which extend beyond the edge of the coils in the group and bend thereover.

5. In an electrical apparatus, the combination with a core of magnetic material, of electrical windings assembled thereon comprising groups of disk-coils, and an insulating jacket formed of insulating tape about one or more of said groups, said jacket being formed to envelop said groups at'points adjacent the core, and to terminate beyond the edge of said coils where not adjacent the 'core whereby there is provided overhanging portions curving over the exposed edges of the lower and upper coils of the group. I i

In witness whereof, I have hereunto set my hand this 27th day of June 1918.

LOCKE H. BURNHAM. 

